Interestingly, at the DNA methylation level, genes such as PIK3CD, RPS6KB2, KCNN4, KCNC4, CORO1B and BCL2L1 are hypermethylated in memory B cells of CVID individuals relative to healthy individuals, or, in other words, they do not undergo the demethylation in the transition from naive to memory cells observed in healthy individuals. Here, PIK3CD is linked to common variable immunodeficiency.